Spark generating system



June 4, 1935. D. w. RANDOLPH El AL 2,003,456

SPARK GENERATING SYSTEM Original Filed April 22, 1933 Qatented June 4, 1935 PATENTOF FICE sun GENERATING srs'rnm Donald W. Randolph and Hector Rabemna,

Flint, Mich., asslgnors, by mesne assignments, to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application April 22, 1933, Serial No. 667,333 Renewed July 12, 1934 11 Claims.

This invention has to do with ignition systems, such as are used on internal combustion engines. Our system is characterized by the fact that the spark is produced by an electrical impulse of very short duration, so short that the system may also be properly termed a high frequency system. This type of charge is of advantage in ignition circuits because such systems will continue to produce a spark even when the spark in gap is shunted by a large conductance as in the case of a badly fouled plug.

Our circuit consists of a device for receiving a charge of electricity, the device being of such character as to rapidly release the charge. For this purpose we may use a condenser of conventional construction. We provide means for charging the condenser, and also means for permitting its rapid discharge. To the discharge circuit is coupled a circuit containing the igform of a transformer-which steps up the voltage to the amount required by the spark gap.

We may charge the condenser in a number of ways, for example,by means of a motor generator set producing direct current of sufiicient voltage; by means of a high voltage battery, by means of a B eliminator, such as are used in radio sets; by means of a transformer whose primary is supplied with interrupted current from the car battery; by means of a machine for generating static electricity; or by any other known devices. However, because of added cost or inconvenience the known devices with which we are familiar are not entirely satisfactory. We prefer to charge the condenser by a surge of current obtained initially from the usual 6 volt storage battery with which automobiles are now commonly equipped. According to the preferred form of our invention the surge of current is produced by interrupting a circuit including the battery and an inductance. The condenser to be charged is connected to the circuit so as to receive the charge stored 'up in the magnetic field of the inductance. When the contact points of the interrupter are closed the battery supplies current to the inductance, and upon separation of the interrupter contacts the energy stored in the inductance as well as the energy of the battery causes the condenser to become charged. To prevent discharge of the condenser through the charging circuit there is provided in the connection to the condenser a suitable device for preventing back flow. .We prefer to use for this purpose a rectifier of any suitable type. In place of the rectifier we may use a mechanical interniting device, the coupling preferably taking the.

rupter timed to break the circuit to the condenser after it has become charged. This, however, has not proven as satisfactory because of mechanical difliculties involved in designing two interrupters, one of which operates an extremely short 5 time after the other. In the circuit just' described it will usually be necessary to protect the points on the first interrupter by means of the usual small condenser, although this reduces the charge available for the main condenser.

As a modification of our condenser charging circuit we have employed the arrangement of transformer and interrupter commonly used in modern battery ignition systems, in this case arranging the main condenser across the ter- 15 minals of the secondary of the transformer and including in series with them the rectifier or mechanical interrupter heretofore described.

By the above described means we provide for charging of the main condenser to a relatively 20 high voltage with only the usual 6 volt storage battery as the energy-source.

The condenser discharge circuit may include a third interrupter, and the primary of a step-up transformer. The secondary of the transformer is preferably arranged in series with the usual distributor and spark plugs. When the contacts of the interrupter in the discharge circuit are closed, the condenser will discharge its energy through the primary of the transformer, thereby 3.0 producing a surge of current through the secondary and a spark at the plug.

The resulting discharge is of such high frequency that the plugs will continue to operate long after they have become fouled to an extent which would have put them out of action when used with an ordinary ignition system.

In the drawing:

Figure 1 illustrates the preferred form of ignition system.

Figure 2 shows a slightly modified circuit, while Figures 3 and 4 show further modifications.

In Figure 1, I 0 indicates the usual car battery, and I2 indicates the condenser to be charged. The condenser may be of conventional construction. We have successfully used one of 1. mi. capacitance. It indicates a mechanically operated interrupter preferably driven from the internal combustion engine. The points of the interrupter are preferably protected from pitting by means of a small condenser l6. In series with the battery and interrupter is the inductance L preferably provided with an iron core. We have used an inductance in the neighborhood of .006 henry. The condenser I2 is connected across the terminals of the interrupter in series with a rectifier l8, illustrated as in the form of a two-electrode rectifier tube. We have had best success with a mercury vapor rectifier tube of suitable design. If desired we may use instead a copper oxide rectifier, an electrolytic rectifier, or any other suitable type. The filament 20 of the tube is heated by means of a suitable battery.

When the circuit through the inductance L is broken at the interrupter, the condenser 12 receives a charge of high voltage from the inductance. The voltage of the charge is preferably in the neighborhood of 150 to 200 volts, and may be conveniently-obtained by using an inductance having a considerable number of turns, for example 200. The rectifier I8, while permitting the charging of the condenser does not permit reverse fiow of current so that the condenser can only discharge through the circuit now to be described.

The discharge circuit includes, in addition to the condenser l2, a mechanically operated circuit-maker 24 and the primary 26 of a transformer. The secondary 28 of the transformer is arranged in series with distributor 30 and gaps 3| of the spark plugs 32. The transformer may have an air core or an iron core as desired and its ratio of transformation may be, for example, in the neighborhoodof from 15 to 1500. Since the energy content of the condenser I2 is relatively low, the impedance of the primary 26 should be as small as possible.

It will now be apparent that when the condenser I2 is charged in the manner stated, discharge will not take place until the circuit maker 24 is in position to close the discharge circuit. The discharge will take the form of a surge of high frequency current through the primary 26 of the transformer which, in turn, will produce a high voltage high frequency surge through the secondary 28, resulting in the passage of a, spark at the plug electr es. Owing to the high frequency of the disc arge a satisfactory spark will be obtained even though the plug is badly fouled.

. With the described arrangement we have satisfactorily operated an internal combustion engine from the usual storage battery, obtaining improved ignition which is practically immune from short circuiting by fouling of the plugs. The high frequency of the discharge has placed it above the range at which interference with radio apparatus is likely to occur.

As a modification of the circuit just described the current flowing in the inductance L may be supplied by rotation of the. inductance in a magnetic field as in the case of the customary magneto construction.

The circuit of Figure 2 is the same as that of Figure 1, except that the inductance L has exchanged places with the interrupter l4 and its condenser IS. The operation is the same, the condenser 12 being charged by release of energy from inductance L upon breaking of the circuit at interrupter ll. I

Figure 2' as well as the remaining views have been rendered diagrammatic by omitting the showing of distributor 30 and substituting a spark gap for the spark plugs but in actual practice the distributor and plugs will, of course, be used.

v Figure 3 differs from Figure 1 only in the character of the circuit for charging the condenser l2. Here the interrupter I4 is arranged in series with the battery and with the primary 34 of a transformer preferably having a ratio 2 to 1. The secondary 36 of the transformer supplies energy through the rectifier tube I8 to the condenser l2 in the same manner as before. We have likewise shown the usual small condenser l6 bridging the points of the interrupter ll. The objection to this circuit is the added complication of *the transformer 3H6.

The circuit shown in Figure 4 is identical with that shown 'in Figure 3, except that the rectifier I8 is replaced by a mechanical interrupter 40. This circuit depends for its operation on careful timing of the two interrupters II and 40 and the circuit maker 24. Opening the circuit at the first interrupter It causes a high voltage surge through the primary 34 and secondary 36 of the transformer. At this time the secondary is closed at the interrupter 40 so that condenser I2 is charged to the desired potential. As soon as the condenser I2 is charged the charging circuit is broken at interrupter l0, and the condenser discharges through the circuit maker 24, the contacts of which are then closed, and the primary 26 of the transformer in the discharge circuit, this producing a spark at the plug as previously described. This circuit proved difiicult to operate because the interrupters must be so accurately timed with'respect to each other that it is diificult, if not impossible, to maintain them in adjustment for any great length of time. However, experimental work with this circuit proved that a condenser could be charged to the required voltage by the use of a current surge produced from a low voltage battery.

While we have in each case shown the distributor in the secondary circuit of the transformer,

it may if desired be placed in the primary circuit but this is undesirable for it necessitates the use of a transformer for each plug.

It will be understood that each of the circuits shown will ordinarily be completed by suitable ground connections instead of in the manner shown.

The values of capacitance, inductance and so on given in this specification are simply illustrative of one specific application of the invention, and by no means indicate its scope. The scope of the invention is set forth in the following claims.

We claim:

1. In an impulse spark generating system the combination of a condenser, means for charging the condenser comprising" an auxiliary circuit including a source of electrical energy, an inductance and an interrupter arranged in series,

means for connecting the condenser to the auxiliary circuit so as to receive a charge when the circuit is broken at the interrupter, said last named means including means for preventing discharge of the condenser therethrough.

2. In an impulse spark generating system the combination of a condenser, means for charging the condenser comprising an auxiliary circuit including a source of electrical energy, an inductance and an interrupter arranged in series, means for connecting the condenser to the auxiliary circuit so as to receive-a charge when the circuit is broken at the interrupter, said last named means including a rectifier tube for preventing discharge of the condenser but permitting charging thereof.

3. In an impulse spark generating system the combination of a condenser, means for charging the condenser comprising an auxiliary circuit including a source of electrical energy, an inductance and an interrupter arranged in series, means for connecting the condenser to the auxiliary circuit so as to receive a charge when the circuit is broken at the interrupter, said last named means including a mechanical interrupter for breaking said last named connections when the condenser is charged.

4. In an impulse spark generating system the combination of a condenser, means for charging the condenser comprising an auxiliary circuit including a source of electrical energy, an inductance and an interrupter arranged in series, means for connecting the condenser to the inductance so as to receive a charge when the said circuit is broken at the interrupter, said last named means including means for preventing discharge of the condenser therethrough.

5. In an impulse spark generating system the combination of a condenser, means for charging the condenser comprising an auxiliary circuit including a source of electrical energy, an interrupter and the primary of a transformer arranged in series, means for connecting the secondary of the transformer in series with the condenser so that the condenser is charged upon breaking of the circuit at the interrupter and means in the last named circuit for preventing discharge of the condenser. I

6. In an impulse spark generating system the combination of a condenser, means for charging the condenser comprising an auxiliary circuit including a source of electrical energy, an inductance and an interrupter arranged in series, means for connecting the condenser to the auxiliary circuit so as to receivea charge when the circuit is broken at the interrupter, said last named means including means for preventing discharge of the condenser therethrough, and a discharge circuit including said condenser and control means in series therewith adapted to permit discharge of the condenser.

'1. In an ignition system the combination of a condenser, means for charging the condenser comprising an auxiliary circuit including a source of electrical energy, an inductance and an interrupter arranged in series, means for connecting the condenser to the auxiliary circuit so as to receive a charge when the circuit is broken at the interrupter, said last named means including means for preventing discharge of the condenser therethrough, and a discharge circuit including said condenser and control means in series therewith adapted to permit discharge of the condenser, and a circuit'containing an ignition device coupled to said discharge circuit.

8. In an ignition system the combination of a condenser, means for charging the condenser comprising an auxiliary circuit including a source of electrical energy, an inductance and an interrupter arranged in series, means for connecting the condenser in parallel with the interrupter so as to receive a charge when the circuit is broken at the interrupter, said last named means including means for preventing discharge of the condenser therethrough, and a discharge circuit including said condenser and control means in series therewith adapted to permit discharge of the condenser and a circuit containing an ignition device inductively connected to said condenser and discharge circuit.

9. In an ignition system the combination of a source of electrical energy, a condenser, connections between the source and the condenser permitting charging thereof, said connections including means to positively prevent discharge of the condenser therethrough, a discharge circuit for the condenser including means for controlling the discharge thereof, and a work circuit including an ignition device, coupled to the condenser discharge circuit.

10. In an ignition system the combination of a source of electrical energy, a condenser, connections between the source and the condenser permitting charging thereof, said connections including means to positively prevent discharge of the condenser therethrough, a discharge circuit for the condenser including means for controlling the discharge thereof, and the primary of a step-up transformer arranged in series, and a work circuit including, in series, the secondary of the transformer and an ignition device.

11. In an ignition system the combination of a source of electrical energy, a condenser, connections between the source and the condenser permitting charging thereof, said connections including means to positively prevent discharge of the-condenser therethrough, a discharge circuit for the condenser including means for controlling the discharge thereof, a work circuit inductively coupled to the discharge circuit, and a distributor and igniting devices arranged in series in said work circuit. DONALD W. RANDOLPH.

HECTOR RABEZZANA. 

